I have the 16" alloys on my Multispace and although the pressure warning systems are working fine, ideally I would like the system de-activated as I don't fancy the cost of replacing four of them when the internal batteries expire (nearly six years old now).

Does anyone know of someone on the south coast who can plug in a computer and do this?

It was a nightmare getting a tyre company to replace the tyres recently as most were worried about damaging the units. Luckily National Tyres were happy to change them.

If a tyre pressure drops below 2Bar, a warning comes on telling which wheel is causing the problem and an orange triangle illuminates until pressure is raised. If the spare wheel is fitted, the warning system goes off at regular intervals saying the system is disabled, very annoying!

The plastic sensor is about the size of a slim matchbox that is part of the tyre valve and sits in a pocket inside the alloy wheel, I guess to keep balance about right. They have an internal battery which activates when the wheel is revolving. I don't know what the battery life is, but I believe they cannot be replaced, the whole sensor needs renewing and then activated to the car.

If anyone has these, be aware that if you have a new tyre fitted and the company are not aware, the sensor can easily be destroyed.

It's a shame that you find the system annoying, when it is telling you of a very important fact, that your tyre is going down ???
TPMS is soon to become compulsory on all new vehicles, as it is a great aid to safety & fuel consumption. When more manufacturers use the system , the parts will become considerably cheaper, an ABS sensor is now about £20, when 15 yrs ago it was £150.
I fear the fault lies with the Neanderthal tyre fitters, because quite frankly it takes about 1% of thought! not to damage a valve when changing a tyre.

Perhaps if you care to read more carefully you will see I said its annoying when the spare wheel is fitted, which doesn't have the sensor. A price drop in 15 years time is a lot of use to me when I need 4 sensors now.